The following relates to printing systems. It finds particular application to automatically de-energizing selective portions of a multi-print (electrophotographic and xerographic or ink jet) engine printing platform while providing other portions of the platform with power to process print jobs.
In a typical xerographic system, such as a copying or printing device, an electronic image is transferred to a print medium, such as paper, plastic, velum and the like. In a xerophotographic process, a photoconductive insulating member is charged to a uniform potential and exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member, which corresponds to the image areas contained within the document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with developing powder referred to in the art as toner. This image may be transferred to a support surface, such as paper, to which the toner image is permanently affixed in a fusing process.
In a multicolor electrophotographic process, successive latent images corresponding to different colors are formed on the insulating member and developed with a respective toner. Each single color toner image is transferred to the paper sheet in superimposed registration with the prior toner image. For simplex printing, only one side of a sheet is printed, while for duplex printing, both sides are printed. Other printing processes are known in which the electronic signal is reproduced as an image on a sheet by other means, such as through impact (e.g., a type system or a wire dot system), or through use of a thermosensitive system, ink jets, laser beams, or the like.
To meet demands for higher outputs of printed pages, one approach has been to increase the speed of the printer, which places greater demands on each of the components of the printer. Another approach has been to develop printing systems which employ several marking engines. The multiple marking engine systems enable high overall outputs to be achieved by printing portions of the same document on multiple printers. Such systems are commonly referred to as “tandem engine” printers, “parallel” printers, or “cluster printing,” in which an electronic print job may be split up for distributed higher productivity printing by different printers, such as separate printing of the color and monochrome pages. Such a system feeds paper from a common source to a plurality of printers, which may be horizontally and/or vertically stacked. Printed media from the various printers is then moved from the printers to a finisher where the sheets associated with a single print job are assembled.
In some multi-marking engine systems, print jobs associated with an inoperable printer are re-routed to an operating printer in order to maintain continuous operation as described in U.S. Pat. No. 5,150,167, “Image Forming Apparatus,” Gonda, et al. However, Gonda, et al. simply checks whether a printer is able to continue an on-going printing process, and if it is not due to lack of paper, empty toner, etc., the printing process is routed to another printer to provide continuous printing.
During scheduled and/or emergency service for conventional printers, copiers and/or multifunction devices, electrical power is removed or limited to the printers for safety reasons. For example, power is removed from a marking engine being replaced by a service technician to mitigate electrical shock. Typically, removing or limiting power to a conventional printer, copier or multifunction device disables its printing capabilities. For instance, in a system with twenty marking engines modules, a single malfunctioning component (e.g., software and/or hardware) may result in power removal from the entire printing system until the component is fixed or replaced. During periods of down time, print jobs are delayed, which results in customer annoyance, decreased customer utility, and loss in revenue. This problem is exacerbated when considered in light of a population of printing platforms.